Procurement of steelmaking raw materials in Taiyuan Iron and Steel Plant, Shanxi Province

1. Classification by smelting method: open hearth steel: including carbon steel and low alloy steel. According to the different lining materials, it can be divided into acid open hearth steel and alkaline open hearth steel. Converter steel: including carbon steel and low alloy steel. According to the position of oxygen blowing, converter steel has three types: bottom blowing, side blowing and oxygen top blowing. Electric furnace steel: mainly alloy steel. According to the different types of electric furnaces, there are four kinds of electric arc furnace steel, induction furnace steel, vacuum induction furnace steel and electroslag furnace steel. Boiling steel, killed steel and semi-killed steel: differentiated by deoxidation degree and gating system. 2. Classification by chemical composition: carbon steel: it is an alloy of iron and carbon. It is reported that in addition to iron and carbon, it also contains elements such as silicon, manganese, phosphorus and sulfur. According to the different carbon content, it can be divided into three kinds of low-carbon (C: 0.60%) steel. Steel with carbon content below 0.04% is called industrial pure iron. Ordinary low alloy steel: a small amount of alloying elements (such as silicon, calcium, titanium, niobium, boron and rare earth elements, etc. The total amount does not exceed 3%) is added on the basis of low-carbon plain carbon steel. Steel grades with better comprehensive properties can be obtained. Alloy steel: It is a kind of steel containing one or more appropriate alloying elements and has good special properties. According to the total content of alloying elements, it can be divided into low alloy (total: 10%) steels. 3. Classification by use: Structural steel: According to different uses, it can be divided into construction steel and mechanical steel. Building steel is used to build boilers, ships, bridges, factories and other buildings. Mechanical steel is used to manufacture machines or mechanical parts. Tool steel: high carbon steel and medium carbon steel used for manufacturing various tools, including carbon tool steel, alloy tool steel and high-speed tool steel. Special steel: special steel with special physical and chemical properties, including stainless acid-resistant steel, heat-resistant steel, electrothermal alloy and magnetic material. Common smelting methods 1, converter steelmaking: a steelmaking method mainly using liquid pig iron as raw material without external heat source. Its main feature is to use the physical heat of liquid pig iron in the converter and the heat generated by the chemical reaction between various components in pig iron such as carbon, manganese, silicon and phosphorus and oxygen sent into the furnace as the smelting heat source to make steel. In addition to molten iron, there are slagging materials (lime, timely, fluorite, etc. ); In order to adjust the temperature, scrap steel and a small amount of cold pig iron and ore can also be added. Converter can be divided into alkaline (lined with magnesia or dolomite) and acidic (lined with siliceous materials) according to the properties of refractory lining. According to the gas blown into the furnace, it is divided into bottom blowing, top blowing and side blowing; According to the gas used, it is divided into air converter and oxygen converter. Acid converter can't remove sulfur and phosphorus from pig iron, so it must use high-quality pig iron, so its application range is limited. Basic converter is suitable for steelmaking with high phosphorus pig iron, which has been greatly developed in western Europe. Because of the high nitrogen content and limited raw materials, the blown converter steel can not be mixed with more scrap steel, which has not been popularized internationally. Oxygen top-blown converter came out in 1952, and now it has become the main steelmaking method in the world. On the basis of oxygen top-blown converter steelmaking, in order to blow high phosphorus pig iron, lime powder oxygen top-blown converter steelmaking appeared. With the successful development of oxygen bottom blowing port technology, Germany and France built oxygen bottom blowing converters in 1967 respectively. After introducing this technology in 197 1 year, the United States developed a converter with bottom blowing oxygen and lime powder for smelting phosphorus-containing pig iron. 1975, France and Luxembourg successfully developed the top-bottom combined blowing converter steelmaking method. 2. Oxygen top-blown converter steelmaking: a converter steelmaking method using pure oxygen to blow molten iron into steel from the top of the converter, or LD method; In the United States, it is usually called BOF method, also known as BOP method. This is the main method of modern steelmaking. The furnace is an upright crucible-shaped container, and an upright water-cooled oxygen gun is inserted into the furnace from the top to supply oxygen. The furnace body can be tilted. The charge is usually molten iron, scrap steel and slagging materials; A small amount of cold pig iron and iron ore can also be added. Blow high-pressure pure oxygen (containing more than O 299.5%) downward from the top of the molten pool with an oxygen lance, remove silicon, manganese, carbon and phosphorus from the molten iron by oxidation, and slag for dephosphorization and desulfurization. The heat generated by the oxidation of various elements heats the liquid metal in the molten pool, making the molten steel reach the current chemical composition and temperature. Mainly used for smelting non-alloy steel and low alloy steel; But through refining, it can also be used to smelt alloy steel such as stainless steel. 3. Oxygen bottom blowing converter steelmaking: a converter steelmaking method in which oxygen is blown into the molten pool in the furnace through the oxygen nozzle at the bottom of the converter to smelt molten iron into steel. Its characteristics are: the height and diameter of the furnace are relatively small; The furnace bottom is flat and can be quickly disassembled and replaced; The tuyere, distributor system and oxygen supply system on the furnace body replace the oxygen lance system of the oxygen top-blown converter. Oxygen bottom-blown converter has the advantages of smooth blowing, less splashing, less smoke and dust, low iron oxide content in slag, and higher metal yield 1% ~ 2% than oxygen top-blown converter. The use of powdery slagging materials, because of its fine particles and large specific surface area, increases the reaction interface, so slagging is fast, which is beneficial to desulfurization and dephosphorization. This method is especially suitable for blowing medium phosphorus pig iron, so it is most widely used in western Europe. 4. Continuous steelmaking: No matter how many heats, raw materials (molten iron and scrap steel) are continuously added from one end of the furnace and finished products (molten steel) are continuously discharged from the other end of the furnace. The idea of continuous steelmaking process is %D%A earlier.